Inferring Cortical Feed-Forward and Feedback Processes with Human Neuroimaging

描述（由申请人提供）：与人脑中的信息流相关的一个中心问题是：自下而上和自上而下的影响如何在大脑皮层中相互作用？提出了一个假设，可以形成一种新的方式来使用非侵入性神经成像来解决这个问题的基础。具体而言，由磁和脑电图（MEG，EEG）检测到的电流偶极子的方向预计是所测量的激活是皮层中自上而下（反馈）还是自下而上（前馈）流的结果的函数。这一假说是建立在这样一个原则上，即前馈和反馈连接到一个皮质区有特点的层状模式的突触输入。因此，知道哪一个皮层层接收到某个输入可以高度地提供关于该输入的来源的信息，并且更一般地关于皮层间通信。这种对层状结构的了解超出了人类神经成像的分辨率。然而，不同类型的层流输入可能导致具有不同极性的宏观偶极子的提议具有提供强大的非侵入性解决方案的潜力。整体假设评估使用三种不同的方法：生物病理学现实的计算建模（目标1），比较体感MEG/EEG响应与颅内灵长类动物的记录（目标2），并评估来自视觉对象感知的认知神经科学理论的MEG/EEG源的极性的实验预测（目标3）。这项研究有望实现对皮层区域网络中信息流的非侵入性推断。这将为脑磁/脑电记录应用于认知加工研究提供一种新的途径，并将脑磁/脑电记录应用于脑的大尺度整合理论中进行解释。它可以导致更好地理解认知功能的神经机制，以及揭示神经疾病机制的潜在应用。

DESCRIPTION (provided by applicant): A central question related to information flow in the human brain is: how do bottom-up and top-down influences interact in the cerebral cortex? A hypothesis is proposed that could form the basis for a novel way to use non-invasive neuroimaging to address this question. Specifically, the direction of the current dipoles detected by magneto- and electroencephalography (MEG, EEG) is expected to be a function of whether the measured activation is a result of top-down (feedback) or bottom-up (feed-forward) flow in the cortex. This hypothesis is founded on the principle that feed-forward and feedback connections into a cortical area have characteristic laminar pattern of synaptic inputs. Consequently, knowing which of the cortical layers received a certain input could be highly informative about the source of this input, and more generally about inter- cortical communication. Such insights about the laminar structure are beyond the resolution of human neuroimaging. However, the proposal that the different types of laminar inputs might result in macroscopic dipoles with different polarities has the potential to provide a powerful non-invasive solution. The overall hypothesis is evaluated using three different approaches: biophysically realistic computational modeling (Aim 1), comparison of somatosensory MEG/EEG responses with intracranial primate recordings (Aim 2), and evaluation of experimental predictions about the polarity of MEG/EEG sources derived from a cognitive neuroscience theory of visual object perception (Aim 3). This research is anticipated to enable non-invasive inference of information flow in networks of cortical areas. It will provide a novel way to apply MEG/EEG recordings to studies of cognitive processing and interpret MEG/EEG in the context of large-scale integrative theories of the brain. It could lead to a better understanding of the neural mechanisms underlying cognitive functions, as well as to potential applications for revealing mechanisms of neural disorders.